Wednesday, November 9, 2011

Image 1: As a toddler you already knew - "Sleep is the most anabolic agent there is"; Sleep - Train - Eat, repeat! Remember that ;-)

If you like Dave Palumbo's Heavy Muscle Radio, you will probably have heard an advertisement that (a few other questionable statements aside) contains a real gem of wisdom: "Sleep is the most anabolic agent there is!" But how come? Well, if you remember the comments I made on the way your muscles grow by both, increasing mononuclear domain sizes (protein synthesis) and the accumulation of new myonuclei, you will probably also remember that, next to estrogen, nitric oxide and a handful of other factors, growth hormone, in general, and the IGF-1 (and MGF-1) that is locally released in response to its secretion, are the primary drivers of satellite cell driven muscle hypertrophy (and possibly hyperplasia)... now, guess when your body produces the lion share of growth hormone (and downstream IGF-1?) in a given day?

You got it, in those cosy (hopefully) ~8 hours you are snorkeling away in between your sheets (Cauter. 1998) - it is in these hours, that your GH levels spike at 600% of their daytime average and your cortisol levels plummet into the abyss. As studies show, this is yet not the only thing on which you are missing out if you do not get your share of quality sleep day in, day out: Even short-term (let alone chronic) sleep deprivation has been shown to significantly increase rates of perceived exertion in athletes and - and this may be even more detrimental - decrease insulin sensitivity and glucose tolerance(VanHelder. 1989). So that after nights and nights of low-quality or insufficient sleep, your secret weapon against tiredness, your pre-workout high-carb-get-me-going shake will no longer get you going in the gym, but rather out of the gym and right to your doctor to ask him for a script for some Metformin to get your blood sugar levels back to normal.

Assuming that I now got your full attention, I want to share the results of two very recent studies with you. One on the differential effect of strength and endurance training in the morning (10am) on sleep quality and duration in 15 healthy trained men (Roveda. 2011) and a second one on the beneficial effects even a single session of resistance training (at 60%RM) has on the sleep pattern of 22 65-85 year old men (Viana. 2011).

Always remember: Sleep is the most anabolic agent there is

One thing upfront: A reasonable amount of physical activity will - regardless of your age and fitness level - make it easier to fall asleep, lengthen the time you spent in bed actually sleeping and not tossing and turning, and contribute to an overall improvement in sleep quality.

As figure 1 goes to show there was a distinct effect of both strengthand endurance training on the time spend in bed (assumed sleep) and the actual sleep time on the first day after the physical activity. In that, it is particularly noteworthy that the actual sleep time increased by +8% and +12.5% and thusly ~2% more than the time the subjects spent in bed. This increase in sleep quality is something we also see in the older subjects of the Viana study, whose REM latency, i.e. the time it took them to enter into the valuable rapid eye movement phase of their sleep, decreased by a whopping -48%, on days on which they had performed their 3 sets of 12 reps (60%RM) of chest presses, leg presses, vertical tractions, leg curls, biceps curls, abdominal crunches, arm extension, and lower back exercises.

Figure 2: Relative changes in sleep efficiency and sleep latency on day 1 and day 2 after a 10am strength or endurance training session in 15 healthy young men (data calculated based on Roveda. 2011).

Now, while we see a "rebound" effect (a decrease in sleep time) in the 2nd night after the morning exercise in the young subjects (comparative data were not collected in the Viana study), the increase in sleep efficiacy, i.e. the amount of time the young men spent in bed vs. the amount of time they actually sleep persisted (cf. figure 2)! And the sleep latency, i.e. the time it took the subjects to fall asleep was still significantly reduced on day 2 after the respective physical activities.

Although there probably is no doubt that physical activity may benefit sleep quality and sleep quality in turn may benefit not only the performance during the former, but also its effects on your metabolic health and body composition (cf. image 1), it is still a matter of constant debate how much, is too much - after all, both forms of overtraining, the sympathetic form, which puts you into a chronic fight and flight mode and will wreak havoc on both your sleep quality and its duration (usually associated with higher intensity training than the bench pressing session 10min warm-up + 4x80%RM the Rovenda subjects performed) and the parasympathetic form, which is what people usually refer as "burnout syndrome" and will have you sleep hours after hours waking totally unrefreshed, produce quite distinct, yet of many athletes carelessly overlooked sleeping patterns, which - and here lies the culprit, still appear to be one of the best, yet by far not "objective" measures of whether you are "hitting your sweet spot" or are just digging a deep black hole by keep pushing and pushing, when your batteries have long run out of energy (Urhausen. 2002)... but this, my friends is a topic for another blog post ;-)

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